Case Depth Prediction of Nitrided Samples with Barkhausen Noise Measurement

Abstract

Nitriding is a heat treatment process that is commonly used to enhance the surface properties of ferrous components. Traditional quality control uses sacrificial pieces that are destructively evaluated. However, efficient production requires quality control where the case depths produced are non-destructively evaluated. In this study, four different low alloy steel materials were studied. Nitriding times for the samples were varied to produce varying case depths. Traditional Barkhausen noise and Barkhausen noise sweep measurements were carried out for non-destructive case depth evaluation. A prediction model between traditional Barkhausen noise measurements and diffusion layer hardness was identified. The diffusion layer hardness was predicted and sweep measurement data was used to predict case depths. Modelling was carried out for non-ground and ground samples with good results.

Attenuation of Barkhausen Noise Emission due to Variable Coating Thickness

“…For instance, thermal softening of hardened components increases MBN [17], whereas surface hardening decreases MBN [18,19]. Stupakov [20] reported on the marked contribution of the surface decarburized layer to the MBN, whereas Santa-aho [21] demonstrated a decrease of MBN as a result of the thin layer containing only non-ferromagnetic nitrides on the surface after plasma nitridation. The plasma nitriding process produces a surface layer of several micrometers in thickness and this layer, together with alteration of the underlying diffusion layer, decreases MBN [22,23].…”

Ensuring the High Strength Characteristics of the Surface Layers of Steel Products

“…Diffusion coating on the surface of the product formed because of saturation of the material of the various elements: nonmetals, metals, and the joint saturation of the elements [15]. The nitriding process is carried out in gas, liquid, and powder media [16]. Partially dissociated ammonia, ammonia and nitrogen, ammonia, and carbonaceous gases are used for gas nitriding [17].…”

Magnetic Measurement of Zn Layer Heterogeneity on the Flange of the Steel Road Barrier

“…Čillikova et al [ 14 ] also demonstrated that the MBN technique is sensitive to the coating generated under the variable regimes of heat treatment, and MBN is a function of matrix softening during annealing. Santa-aho [ 15 ] reported a decrease of MBN when the thin layer of non-ferromagnetic nitrides can be found on the surface. The nitriding process produces the thin nitriding layer and underlying diffusion layer, which decreases MBN [ 16 , 17 ].…”